Organic electro-luminescence display device

ABSTRACT

An organic electro-luminescence display device includes a first substrate, plural pedestals which are provided in a convex shape on the first substrate and have inclined side surfaces, plural first electrodes respectively provided on the respective side surfaces of the pedestals, an organic electro-luminescence film which is provided above the plural pedestals and includes a light-emitting layer laminated on the plural fist electrodes, and a second electrode which is provided above the plural pedestals and is laminated on the organic electro-luminescence film. Light generated in the light-emitting layer is transmitted between a first reflection surface and a second reflection surface. The second electrode includes light transmission parts, through which the light passes, above upper end parts of the pedestals. A surface of the second electrode facing the organic electro-luminescence film is the second reflection surface except for the light transmission parts.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese applicationJP2013-251199 filed on. Dec. 4, 2013, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an organic electro-luminescence displaydevice.

2. Description of the Related Art

An organic electro-luminescence display device has a structure in whichan organic film is sandwiched between an anode and a cathode (see JP2012-234748 A). In general, plural organic films are laminated, and onelayer thereof is a light-emitting layer. The organic film is coveredwith a translucent sealing film and is shielded from moisture.

In a high quality display device, a pixel is micronized, so thatadjacent pixels are close to each other. Thus, light generated in one ofthe pixels is transmitted through the sealing film and can enter theadjacent pixel, and a problem of color mixture occurs by this. Hitherto,since about 80% of light is transmitted in a lateral direction or anoblique direction, the efficiency is low.

SUMMARY OF THE INVENTION

The invention has an object to prevent color mixture and to improveefficiency.

(1) An organic electro-luminescence display device of the invention,includes a substrate, plural pedestals which are provided in a convexshape on the substrate and have inclined side surfaces, plural firstelectrodes respectively provided on the respective side surfaces of thepedestals, an organic electro-luminescence film which is provided abovethe plural pedestals and includes a light-emitting layer laminated onthe plural fist electrodes, and a second electrode which is providedabove the plural pedestals and is laminated on the organicelectro-luminescence film, light generated in the light-emitting layeris transmitted between a first reflection surface and a secondreflection surface, the second electrode includes light transmissionparts, through which the light passes, above upper end parts of thepedestals, and a surface of the second electrode facing the organicelectro-luminescence film is the second reflection surface except forthe light transmission parts. According to the invention, since thelight generated in the light-emitting layer is emitted upward of theupper end part of the pedestal, the light is hard to enter an adjacentpixel. By this, color mixture can be prevented and efficiency can beimproved.

(2) In the organic electro-luminescence display device as recited in(1), surfaces of the first electrodes facing the light-emitting layerare the first reflection surface.

(3) In the organic electro-luminescence display device as recited in(2), the light-emitting layer includes plural light-emitting layers eachof which emits light of one of plural colors, and each of the plurallight-emitting layers is laminated on one of the first electrodes.

(4) The organic electro-luminescence display device as recited in (3)further includes an insulation layer provided between the adjacentpedestals and placed on end parts of the adjacent first electrodes.

(5) In the organic electro-luminescence display device as recited in(4), a refractive index of the insulation layer is higher than that ofthe plural light-emitting layers, end parts of the adjacentlight-emitting layers are disposed to be separated from each other andto contact the insulation layer, and the second electrode contacts theinsulation layer between the adjacent light-emitting layers.

(6) In the organic electro-luminescence display device as recited in(1), the light-emitting layer is continuously laminated on the pluralfirst electrodes and emits light of one color.

(7) The organic electro-luminescence display device as recited in (6)further includes a color filter.

(8) The organic electro-luminescence display device as recited in (6)further includes mirror layers arranged below the respective pedestals,the plural pedestals and the first electrode respectively have lighttransmissivity, the plural pedestals include colored layers of pluralcolors to constitute a color filter, and surfaces of the mirror layersfacing the pedestals are the first reflection surface.

(9) In the organic electro-luminescence display device as recited in(8), each of the mirror layers has conductivity and is electricallyconnected to one of the first, electrodes.

(10) The organic electro-luminescence display device as recited in anyone of (6) to (9) further includes an insulation layer which is providedbetween the adjacent pedestals and is placed on end parts of theadjacent first electrodes.

(11) In the organic electro-luminescence display device as recited in(10), a refractive index of the insulation layer is higher than that ofthe light-emit ting layer, and the light-emitting layer is provided tocover the insulation layer.

(12) In the organic electro-luminescence display device as recited inany one of (1) to (11), the plural first electrodes are provided whileavoiding the upper end parts of the plural pedestals.

(13) In the organic electron-luminescence display device as recited in(12), the light-emitting layer is provided while avoiding regions abovethe upper end parts of the plural pedestals.

(14) In the organic electro-luminescence display device as recited in(13), the second electrode is provided while avoiding the regions abovethe upper end parts of the plural pedestals, and the light transmissionparts are openings provided in the second electrode.

(15) In the organic electro-luminescence display device as recited inany one of (1) to (11), the plural first electrodes are provided to beplaced on the upper end parts of the plural pedestals.

(16) In the organic electro-luminescence display device as recited in(15), the light-emitting layer is provided above the upper end parts ofthe plural pedestals to be placed on the plural first electrodes.

(17) In the organic electro-luminescence display device as recited in(16), the second electrode is provided above the upper end parts of theplural pedestals to be placed, on the light-emitting layer, and thelight transmission parts are made of transparent conductive material.

(18) In the organic electro-luminescence display device as recited in(17), the second electrode includes a transparent layer made of thetransparent conductive material and a reflection layer made of materialto reflect light, and the reflection layer is laminated on the organicelectro-luminescence film above the side surfaces of the plural,pedestals while avoiding regions above the upper end parts of the pluralpedestals.

(19) In the organic electro-luminescence display device as recited in(18), the reflection layer contacts the organic electro-luminescencefilm, and the transparent layer is provided to cover the reflectionlayer.

(20) In the organic electro-luminescence display device as recited inany one of (1) to (19), the second electrode has unevennesscorresponding to shapes of the plural pedestals, and a flattening filmis provided in a concave part to nave a thickness equal to a height of aconvex part of the unevenness.

(21) The organic electro-luminescence display device as recited in (20)further includes a sealing film which is provided above the secondelectrode and the flattening film and seals the organicelectro-luminescence film.

(22) In the organic electro-luminescence display device as recited inany one of (1) to (21), each of the plural pedestals has a truncatedshape.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of an organic electro-luminescence displaydevice of a first embodiment of the invention.

FIG. 2 is a sectional perspective view showing a part of a firstsubstrate and a lamination structure thereon.

FIG. 3 is a III-III line sectional view of a structure shown in FIG. 2.

FIG. 4 is a IV-IV line sectional view of the structure shown in FIG. 2.

FIGS 5A to 5C are views for explaining a manufacturing method of theorganic electro-luminescence display device of the first embodiment.

FIG. 6 is an enlarged sectional view of a part of an organicelectro-luminescence display device of a second embodiment of theinvention.

FIG. 7 is an enlarged sectional view of a part of an organicelectro-luminescence display device of a third embodiment of theinvention.

FIG. 8 is an enlarged sectional view of a part of an organicelectro-luminescence display device of a fourth embodiment of theinvention.

FIG. 9 is an enlarged sectional view of a part of an organicelectro-luminescence display device of a fifth embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the invention will be described withreference to the drawings.

First Embodiment

FIG. 1 is a sectional view of an organic electro-luminescence displaydevice of a first embodiment of the invention. The organicelectro-luminescence display device includes a first substrate 10. Thefirst substrate 10 is mounted with an integrated circuit chip 12 fordriving an element for displaying an image. The first, substrate 10 isconnected with a flexible wiring board 14 for electrical connection withthe outside. A circuit layer 16 including a not-shown thin filmtransistor, a wiring and an insulation layer is formed on the firstsubstrate 10. An element layer 18 is laminated on the circuit layer 16.The details of the element layer 18 will be described later.

The display device includes a second substrate 20. The second substrate20 is arranged to be separated from and to face the first substrate 10.A filler 22 is provided between the first substrate 10 and the secondsubstrate 20, and the filler 22 is surrounded and sealed by a sealmember 24.

FIG. 2 is a sectional perspective view showing a part of the firstsubstrate and the lamination structure thereon. FIG. 3 is a III-III linesectional view of the structure shown in FIG. 2. FIG. 4 is a IV-IV linesectional view of the structure shown in FIG. 2.

The element layer 18 includes plural pedestals 26. The plural pedestals26 are formed in a convex shape on the first substrate 10. Each of thepedestals 26 is made of a resin such as acrylic resin. The pedestal 26may have light transmissivity or may have light shielding property. Thepedestal 26 is formed in a truncated shape such as a truncated cone or atruncated pyramid, The pedestal 26 includes an inclined side surface.The side surface of the truncated conical pedestal 26 has a taper shape.An upper end part of the pedestal 26 has a flat upper surface. Theplural pedestals 26 are arranged in matrix to form plural rows andplural columns.

A first electrode 28 (anode) is provided on the side surface of thepedestal 26. The first electrode 28 is placed also on the upper end partof the pedestal 26. The first electrode 28 reflects light. Particularly,the first electrode 28 is made of a single layer of metal such as silveror aluminum, and the surface (surface on the side opposite to thepedestal 26) may reflect light. Alternatively, if the first electrode 28is formed of plural layers, the outermost layer is formed of transparentconductive material such as indium tin oxide or indium zinc oxide, and asurface of a lower layer made of metal such as silver or aluminum, mayreflect light. In any case, the first electrode 28 includes a firstreflection surface 30 to reflect light on the side opposite to thepedestal 26.

The first electrode 28 is connected to a not-shown thin film transistorthrough a not-shown wiring of the circuit layer 16. The first electrode28 is provided to protrude from the pedestal 26. The uppermost layer ofthe circuit layer 16 is a passivation film made of, for example, SiO₂,and the end part of the first electrode 28 is placed thereon.

An insulation layer 32 is provided between the adjacent pedestals 26 andis placed on the end parts of the adjacent first electrodes 28. Forexample, the insulation layer 32 is placed on the portion of the firstelectrode 28 protruding from the pedestal 26. In this example, theinsulation layer 32 is located at a position not overlapping thepedestal 26. In other words, as shown in FIG. 2, the insulation layer 32is provided on the circuit layer 16 so as to avoid the pedestals 26. Ifthe insulation layer 32 has light transmissivity, the insulation layeris made of material having high refractive index, such as siliconnitride.

Organic electro-luminescence films 34 are provided above the pedestals26. Although not shown, the organic electro-luminescence film 34includes plural layers which include at least a light-emitting layer andfurther include at least one of an electron transport layer, a holetransport layer, an electron injection layer and a hole injection layer.The plural organic electro-luminescence films 34 are provided so thateach of the light-emitting layers emits light of one of plural colors.Accordingly, the plural light-emitting layers generate lights of pluralcolors.

The light-emitting layer is provided, to be placed also on. an upper endpart of the pedestal 26. Since the pedestal 26 is provided in a convexshape, the surface is wider than the bottom surface. Thus, the organicelectro-luminescence film 34 (light-emitting layer) can be providedwidely, and accordingly, the light emission efficiency is improved. Bythis, high brightness can be obtained, or the life can be prolonged byreducing current density.

The organic electro-luminescence file 34 (light-emitting layer) islaminated on the first electrode 28. Respective end parts of theadjacent organic electro-luminescence films 34 (light-emitting layers)are separated from each other and are arranged so as to contact theinsulation layer 32. The refractive index of the light-emitting layer islower than the refractive index of the insulation layer 32. Therefractive index of the insulation layer 32 is higher than therefractive index of the light-emitting layer. Since the refractiveindexes of the light-emitting layer and the insulation layer 32 aredifferent from each other, the light generated in the light-emittinglayer is liable to be reflected at the interface between thelight-emitting layer and the insulation layer 32. Accordingly, even ifthe insulation layer 32 has light transmissivity, the light generated inthe light-emitting layer is hard to pass through the insulation layer32.

A second electrode 36 (cathode) is laminated above the plural pedestals26 and on the organic electro-luminescence film 34 (light-emittinglayer). The second electrode 36 is made of metal such as silver oraluminum, and reflects light. Particularly, the second electrode 36includes a second reflection surface 38 to reflect light on the sidefacing the organic electro-luminescence film 34 (light-emitting layer).

A voltage is applied to the first electrode 28 and the second electrode36, so that holes and electrons are injected into the organicelectro-luminescence film 34. The injected holes and electrons arecombined in the light-emitting layer and light is emitted. Since theinsulation layer 32 intervenes between the end part of the firstelectrode 28 and the second electrode 36, short circuiting between thetwo is prevented.

The organic electro-luminescence film 34 (light-emitting layer) issandwiched between the first reflection surface 30 and the secondreflection surface 38. The surface of the first electrode 28 on the sidefacing the light-emitting layer is the first reflection surface 30. Thesurface of the second electrode 36 on the side facing the organicelectro-luminescence film 34 (light-emitting layer) is the secondreflection surface 38. The first reflection surface 30 and the secondreflection surface 38 constitute a light cavity. The light generated inthe light-emitting layer is transmitted between the first reflectionsurface 30 and the second reflection surface 38, and light of a specificwavelength is amplified.

The second electrode 36 is provided so as to avoid a region above theupper end part of the pedestal 26. The second electrode 36 includes alight transmission part 40, through which light passes, above the upperend part of the pedestal 26. The light transmission part 40 is anopening formed in the second electrode 36. The light generated in theorganic: electro-luminescence film 34 (light-emitting layer) is emittedfrom the light transmission part 40 of the second electrode 36. Sincethe light is transmitted between the first reflection surface 30 and thesecond reflection surface 38, the light is emitted uniformly in alldirections. Thus, wide viewing angle characteristics can be obtained.Besides, since a light emission region is limited to the lighttransmission part 40, light leakage cam be prevented.

According to this embodiment, since the light generated in thelight-emitting layer is emitted upward of the upper end part of thepedestal 26, the light is hard to enter the adjacent pixel. By this,color mixture can be prevented and efficiency can be improved.

The second electrode 36 contacts the insulation layer 32 between theadjacent light-emitting layers. The second electrode 36 is formed, tohave unevenness corresponding to the shape of the plural pedestals 26. Aflattening film 42 is provided in a concave part so as to have a heightequal to the height of a convex part of the unevenness of the secondelectrode 36. The upper surface of the flattening film 42 is flush withthe highest upper end surface (peripheral edge surface of the opening)of the convex part of the second electrode 36 and the highest uppersurface (surface above the upper end part of the pedestal 26) of theorganic electro-luminescence film 34 (light-emitting layer). Since theflattening film 42 has light transmissivity, external light enters. Thelight entering the flattening film 42 is scattered by the unevenness ofthe second electrode 36, reduction of visibility by reflected light canbe suppressed.

A sealing film 44 is provided above the second, electrode 36 and theflattening film 42. The sealing film 44 seals and shields the organicelectro-luminescence film 34 from moisture. The sealing film 44 may beformed of one layer or may be formed of plural layers. A lower surfaceof the sealing film 44 contacts the organic electro-luminescence film 34(light-emitting layer) in the opening of the second electrode 36.

FIGS. 5A to 5C are views for explaining a manufacturing method of theorganic electro-luminescence display device of the first embodiment.

As shown in FIG. 5A, the circuit layer 16 is formed on the firstsubstrate 10, and the plural pedestals 26 are formed on the circuit,layer 16. The pedestals 26 are made of resin, and nanoimprint may beused as a forming method thereof. Next, the first electrodes 28 areformed on the pedestals 26. The first electrodes 28 are formed bypatterning, for example, by etching a conductive film formed so as tocover the pedestals 26 . The lower end parts of the first electrodes 28are formed to protrude from the pedestals 26, and the insulation layer32 is formed to be placed thereon. Then, the organicelectro-luminescence films 34 are formed by evaporation or sputtering.The organic electro-luminescence films 34 are formed to includelight-emitting layers and to cover the first electrodes 28. As shown inFIG. 5B, the second electrode 36 is formed so as to have the openingabove the upper end part of the pedestal 26. Then, as shown in FIG. 5C,the flattening film 42 is formed. Thereafter, as shown in FIG. 4, thesealing film 44 is formed. The details of the manufacturing methodinclude contents obvious from the description of the apparatus.

Second Embodiment

FIG. 6 is an enlarged sectional view of a part of an organicelectro-luminescence display device of a second embodiment of theinvention. In this embodiment, plural first electrodes 228 are providedso as to avoid upper end parts of plural pedestals 226, Organicelectro-luminescence films 234 (light-emitting layers) are provided soas to avoid regions above upper end parts of the pedestals 226. Theseare different from the first embodiment.

The other details are the same as the contents described in the firstembodiment. For example, a second, electrode 236 is provided so as toavoid the region above the upper end part of the pedestal 226. A lighttransmission parts 240 is an openings formed in the second electrode236.

Third Embodiment

FIG. 7 is an enlarged sectional view of a part of an organicelectro-luminescence display device of a third embodiment of theinvention. In this embodiment, an organic electro-luminescence film 334is continuously laminated on plural first electrodes 328, and alight-emitting layer emits light of one color (for example, white). Acolor filter 346 is provided on a second substrate 320 in order toperform full-color image display. The color filter 346 includes a blackmatrix 348 and a colored layer 350 of plural colors. These are differentfrom the first embodiment. The other details are the same as thecontents described in the first embodiment.

Fourth Embodiment

FIG. 8 is an enlarged sectional view of an organic electro-luminescencedisplay device of a fourth, embodiment of the invention.

In this embodiment, an organic electro-luminescence film 434(light-emitting layer) is placed on first electrodes 428 above upper endparts of pedestals 426 and is continuously laminated on the plural firstelectrodes 428. A light-emitting layer emits light of one color (forexample, white).

The first electrodes 428 are provided so as to be placed also on theupper end parts of the pedestals 426. The first electrodes 428 are madeof transparent conductive material such as indium tin oxide or indiumzinc oxide, and have light transmissivity. Accordingly, light generatedin the light-emitting layer passes through the first electrodes 428.

Each of the plural pedestals 426 has light transmissivity, and allowslight of a specific wavelength to pass through. A light of a specificcolor among lights passing through the first electrode 428 passesthrough the pedestal 426. Plural kinds of the pedestals 426 to allowlights of different colors (for example, red, blue and green) to passthrough are provided. That is, the plural pedestals 426 include coloredlayers of plural colors so as to constitute a color filter.

Mirror layers 452 are respectively arranged under the respectivepedestals 426. Surfaces of the mirror layers 452 facing the pedestals426 are first reflection surfaces 430. Light generated in thelight-emitting layer is reflected by the first reflection surface 430 ofthe mirror layer 452, travels through the pedestal 426 and is emittedfrom a light transmission part 440 (opening) of a second electrode 436.The mirror layer 452 has conductivity and is electrically connected toone of the first electrodes 428.

An insulation layer 432 is provided, between the adjacent pedestals 426and is placed on end parts of the adjacent first electrodes 428. Therefractive index of the insulation, layer 432 is higher than that of thelight-emitting layer. The light-emitting layer is provided so as tocover the insulation layer 432. The other details are the same as thecontents described in the first embodiment.

Fifth Embodiment

FIG. 9 is an enlarged sectional view of a part of an organicelectro-luminescence display device of a fifth embodiment of theinvention.

In this embodiment, a second electrode 536 includes a reflection layer554 made of material (metal such, as, for example, silver or aluminum)to reflect light. The reflection layer 554 is provided so as to avoidregions above upper end. parts of plural pedestals 526. The regionswhich the reflection layer 554 avoids are light transmission parts 540of the second electrode 536. The reflection layer 554 is laminated on anorganic electro-luminescence film 534 above side surfaces of pluralpedestals 526. The reflection layer 554 contacts the organicelectro-luminescence film 534.

The second electrode 536 includes a transparent layer 556 made oftransparent conductive material such as indium tin oxide or indium zincoxide. The transparent layer 556 is provided so as to cover thereflection layer 554. The transparent layer 556 is provided so as to beplaced on the organic electro-luminescence film 534 (light-emittinglayer) above the upper end parts of the plural pedestals 526. The lighttransmission part 540 is made of the transparent layer 556 (transparentconductive material).

Although tin is embodiment is an example in which the second electrode536 including the reflection layer 554 and the transparent layer 556 isapplied to the fourth embodiment, this feature can be applied to anyother embodiments.

While there have been described what are at present considered to becertain embodiments of the invention, it will be understood that variousmodifications may be made thereto, and it is intended that the appendedclaims cover all such modifications as fall within the true spirit andscope of the invention.

What is claimed:
 1. A display device comprising: a substrate including aplurality of pixels, each of the plurality of pixels comprising: aconvex portion located on the substrate, and having an upper surface anda side surface; a first electrodes located on at least the side surface;a light-emitting layer having a first main surface and a second mainsurface opposite to the first main surface, the first main surfacefacing at least the side surface via the first electrode; a firstreflection surface facing the first main surface; a second reflectionsurface facing the second main surface; and a second electrode locatedabove at least the side surface via the light-emitting layer and thefirst electrode, including the second reflection surface, and having anopening above the upper surface.
 2. The display device according toclaim 1, wherein the first reflection surface is a surface of the firstelectrode.
 3. The display device according to claim 1, furthercomprising an insulation layer provided between two of the pixelsadjacent each other, wherein the insulation layer covers an end part ofthe first electrode.
 4. The display device according to claim 1 furthercomprising a mirror layer arranged below the convex portion, wherein themirror layer includes the first reflection surface.
 5. The displaydevice according to claim 4, wherein the first electrode has lighttransmissivity, and the convex portion includes a color filter.
 6. Thedisplay device according to claim 4, wherein the mirror layer hasconductivity and is electrically connected to the first electrode. 7.The display device according to claim 1, wherein the first electrode andthe light-emitting layer are not located above the upper surface.
 8. Thedisplay device according to claim 1, wherein the first electrode islocated on the upper surface, and the light-emitting layer is locatedabove the upper surface via the first electrode.
 9. The display deviceaccording to claim 1, further comprising a transparent conductive layeron the second electrode, wherein the transparent conductive layer facesthe upper surface and the side surface.
 10. The display device accordingto claim 1, wherein the plurality of pixels include a first pixel havinga first convex portion and a second pixel having a second convexportion, the second pixel being adjacent to the first pixel, wherein aconcave part between the first and second convex portions is filled witha flattening film.
 11. The display device according to claim 1, whereinthe convex portion has a truncated shape.
 12. The display deviceaccording to claim 1, wherein light generated in the light-emittinglayer is transmitted between the first reflection surface and the secondreflection surface, and the light passes through the opening.
 13. Adisplay device comprising: a substrate; a plurality of convex portionson the substrate, each of the convex portions having an upper surfaceand a side surface; a plurality of first electrodes each located on atleast the side surface; a light-emitting layer facing at least the sidesurface via one of the first electrodes; and a second electrode facingat least the side surface via the light-emitting layer and the one ofthe first electrodes, wherein the second electrode has an opening abovethe upper surface and a second reflection surface facing thelight-emitting layer.
 14. The display device according to claim 13,wherein each of the first electrodes has a first reflection surfacefacing the light-emitting layer.
 15. The display device according toclaim 13, further comprising a plurality of mirror layers each arrangedbelow each of the convex portions, wherein each of the mirror layers hasa first reflection surface facing the light-emitting layer.
 16. Thedisplay device according to claim 15, wherein each of the mirror layershas conductivity and is electrically connected to each of the firstelectrodes.
 17. The display device according to claim 13, wherein eachof the first electrodes overlaps the upper surface and a side surface.18. The display device according to claim 13, wherein the light-emittinglayer overlaps the upper surface and a side surface.
 19. The displaydevice according to claim 13, wherein the second electrode overlaps theplurality of convex portions.
 20. The display device according to claim13, wherein the first electrodes and the light-emitting layer are notlocated above the upper surface.